In recent years, there have been advances in a reduction in the size of connection terminals in components (for example, electronic components in liquid crystal productions) due to a trend toward miniaturization and higher functionality of electronic appliances. Thus, in the field of electronics packaging, film adhesives are widely used as various anisotropic conductive adhesives capable of easily establishing connections between the terminals. For example, film adhesives are used for the joint between printed circuit boards, such as flexible printed circuit boards (FPCs) and rigid printed wiring boards (PWBs or PCBs), provided with electrodes, such as copper electrodes, for connection using adhesives and interconnection substrates, such as glass substrates, provided with wiring electrodes, such as copper electrodes, and between printed circuit boards and electronic components, such as integrated circuit (IC) chips.
An anisotropic conductive adhesive is an adhesive containing electrically conductive particles dispersed in an insulating resin composition. The anisotropic conductive adhesive is interposed between connection members, heated, and pressurized to bond the connection members to each other. That is, for example, the heating and pressurization allow a resin in the adhesive to flow to seal a gap between an electrode for connection using an adhesive formed on a surface of a printed circuit board and a wiring electrode formed on an interconnection substrate. Simultaneously, some of the electrically conductive particles are arranged between the wiring electrode and the electrode for connection using an adhesive, thereby establishing an electrical connection. Here, each of the electrode for connection using an adhesive of the printed circuit board and the wiring electrode of the interconnection substrate is generally subjected to gold plating in order to achieve prevention of oxidation and electrical conduction properties (for example, see Patent Literature 1).